Heath Ledger was the golden-haired, soft-spoken Australian heartthrob who starred in the late 90s and early 00s hits like "Ten Things I Hate About You" and "A Knight's Tale;" then he moved on to more serious roles, like his Academy Award-nominated performance in "Brokeback Mountain," a breakthrough moment for LGBTQ+ representation in cinema and his Oscar-winning performance as the Joker in Christopher Nolan's sequel to "Batman Begins," 2008's "The Dark Knight" and more.